Endless conveyor belts are commonly formed of urethane and the ends of the belt are joined together by heat and pressure in a heat press to provide an endless configuration. Each end of the belt is initially cut into a series of V-shaped fingers, and the fingers on the two ends of the belt, are then interdigitated or spliced. The spliced joint is then placed in the press, where heat and pressure are applied, causing the urethane to melt and fuse the spliced joint.
The typical heat press used for joining the spliced ends of a conveyor belt includes a lower platen that supports the belt and an upper platen. The belt is clamped between the platens by mechanical clamping members, or alternately, by incorporating an inflatable bladder in the upper platen, and the bladder, when inflated, will force the belt downwardly against the lower platen. Heat is applied to the spliced area by heating elements located in the lower and/or upper platen. In operation, the spliced area of the belt is positioned on the lower platen, and the upper platen is then positioned above the lower platen and clamped to the lower platen. The electrical heating element is then energized to heat and fuse the belt material. After the heating period, the press is cooled either by ambient air cooling or by flowing a cooling medium, such as water or compressed air or a combination of both, through tubes or passages in the lower platen.
The typical heat press as used in the past has several disadvantages. The conventional press has considerable weight so that the press is not portable and thus cannot be used to splice a belt on the conveyor. Instead, the belt must be removed from the conveyor and brought to the site of the heat press. As the conventional heat press has considerable mass, the cycle time for heating and cooling the belt is quite long, generally requiring a cycle time of about one hour for a urethane belt with a thickness of 1/16inch. The excessive mass, as used in the typical heat press, also increases the power requirements for heating and cooling.
In addition, the typical heat press as used in the past has not included automated operation so that an operator's attendance was necessary at all times during the cycle.
If the heat press included water cooling, supply tanks and a recirculation or disposal system were required for the cooling water. On the other hand, if compressed air was utilized for cooling, the exhausting of the high pressure air from the press during the cooling cycle created a noise pollution problem, as well as a potential hazard to employees.